This application claims priority from German Patent Application No. DE 199 62 247, filed Dec. 22, 1999.
The present invention relates generally to a movement transmission apparatus. More specifically, the present invention relates to a movement transmission apparatus for the transmission of at least two input-side movement components, each movement component having one degree of freedom, into one output-side movement with at least two degrees of freedom, or vice versa. Further, the present invention relates to a positioning apparatus formed from a number of individual transmission units that have been functionally coupled with one another in parallel arrangement by means of their respective output sections.
The first mentioned movement transmission apparatus was disclosed by the CH-patent 672089, which described a positioning apparatus with such a movement transmission apparatus. This movement transmission apparatus exhibits three functionally parallel transmission units, which, together permitted a positioning of an output part of the positioning apparatus in three degrees of freedom of movement. This positioning apparatus encompasses per transmission unit a firm base with an actuator, which drives the one movable section of the movement transmission apparatus. The movable section, in turn, exhibits on its own account, two universal jointings and by means of these, is bound to the movable part of the movement transmission apparatus. The actuator swings each transmission unit on its associated, movable section about a corresponding, rotatable axle. The two universal joints of the movable sections are bonded to one another by a rod, permit a movement of each transmission unit in the direction of the swinging movement of the other two transmission units. The combined effect is that the movable output part of this movement transmission apparatus carries out a movement in space, in which the inclination and orientation of this output part remains undisturbed, while the three transmission units continue to be driven. On the bases of this formulation, with swinging axles and universal joints, this movement transmission apparatus does adapt itself, but only conditionally, for precision operations, since these universal linkages can be constructed only with the expenditure of considerable technical effort for the required minimum of movement play.
The second named generic movement transmission apparatus is, for instance, taught by the DE 37 21 682 A1. This publication shows in one embodiment, a movement transmission apparatus with three transmission units, which, on the input-side, respectively, are caused to undergo a linear or plane movement which runs at an angle to the extending direction of the respective transmission unit. The transmission units are comprised of respectively one carrying arm, which, by means of its own solid body swing joint, for instance, a film hinge, is coupled with the input and the output section of the respective transmission unit. The three transmission units are coupled with one another by means of their output sections. With the special formulation of the transmission units, especially the solid body linkage, there arise nevertheless, displacement movements in the micrometer range, which are not sufficiently precisely adjustable and exhibit too much play, i.e. are too loose.
EP 0 937 961 A2 brings into public knowledge a mechanism for a multi-axle positioning apparatus, which possesses a stationary and a movable section, which are bound together, per axle, by a transmission apparatus to carry the force onto the movable section. The transmission units possess two parallel rods of flexible material, which, per rod, respectively encompasses two bendable sections. In this matter, the said rods are composed of hollow tubing, which are interrupted at the bend sections, at which place, a length of piano wire is inserted. The transmission units transmit the force along their extending axes onto the movable part and permit a free movement perpendicular to its extended direction, that is to say, along the axles of the other transmission units.
The U.S. Pat. No. 4,888,878 makes known a positioning apparatus with a movement transmission apparatus, which has the capability of controlling three or more degrees of freedom of movement. In this arrangement, the movement transmission apparatus possesses several functional, in-series connected, transmission units, wherein each, in output to input fashion, is coupled with the next. That transmission unit which lies first in the sequence, possesses an immovable anchor base, and the final transmission unit in the line is coupled to the controlling output element of the movement transmission apparatus. Each transmission unit exhibits a driving means, that drives a movable second section relative to a xe2x80x9csolidxe2x80x9d section. The movable second section is connected with the said xe2x80x9csolidxe2x80x9d section by means of a flexible bend linkage. The disadvantage of this movement transmission apparatus lies therein, in that because of its serial build-up, each transmission unit is burdened with the increasing weight of the sequential transmission units, whereby, the dynamics are disadvantaged by sequentially compounding characteristics.
Thus, there is a continuing need to further improve, in depth, the movement transmission apparatuses of the generic type in their functional parallel kinematics to the end that precision movements are made possible.
A transmission unit assembled in accordance with the teachings of the present invention encompasses a first section and a second, input section linked to the first section by means of a first bend linkage. The first section is movably linked in the direction of the corresponding degree of freedom of movement of the transmission unit. In this system, the second section is so designed, that, by means of a second, output-side bend linkage, the section allows free travel within the degree of freedom of movement.
Further, a movement transmission assembled in accordance with the teachings of the present invention permits the transmission of three input-side movement components with respectively one degree of freedom of movement into an output-side movement with three movement degrees of freedom, or vice versa. Three transmission units, each including one input section and one output section, may be functionally coupled with one another by means of their output sections, with each transmission unit exhibiting an extended direction from its current input section to its respective output section. As a hingedly designed means of linkage, the output section of each transmission unit permits free movements perpendicular to its extension direction, whereby, the input section of the transmission unit is so formulated, that the respective input-side movement is introduced at an angle to the direction of extension.
According to a first aspect of the invention, in a generic type of a first movement transmission apparatus, the first and the second jointing means are designed as bend linkages, and the second section, the second bend linkage means and the output section are so constructed, that in combination they form a rigid structure along the degree of freedom of movement of the input-side of the thereto associated transmission unit.
According to another aspect of the invention, in a second movement transmission apparatus of the generic type, the bend linkages are designed according to the kind of parallelogram-swing linkages, wherein each parallelogram-swing linkage encompasses one bar pair with respectively one bend linkage on all four bar ends. Further in this arrangement, the two respective ends of one bar, by means of the corresponding bend linkage, are respectively coupled with the input section and with the output section. By this arrangement, the rigidity of a transmission unit, and therewith the precision of the entire movement transmission apparatus is advantageously increased. With advantage, the output movement has, in the stated arrangement, a movement component along one of the three degrees of freedom of movement, the travel path of which is greater, when compared to the travel path of the movement component of the two other degrees of freedom.
Certain advantages and features of the disclosed embodiment are described in more detail below, with reference being made to the accompanying drawings.